Non-destructive testing (NDT) and structural health monitoring (SHM) techniques are frequently used to test or inspect a material without causing damage. For example, such NDT/SHM techniques may be used to inspect welds or identify defects in pipes, airplane components, and other devices or materials in which maintaining the integrity of (i.e. not damaging) the device or material is desirable. For the purposes of the present technology, NDT refers to the non-invasive inspection of a structure or component, in which the evaluation of said structure or component is conducted on the data collected during the current inspection period and does not rely on comparison to previous data sets. Furthermore, for the purposes of the present disclosure, SHM refers to one of the permanent installation of a sensor for long-term monitoring of a structure or component or a method in which the evaluation of said structure or component relies on a comparison between data collected on said structure or component from an equivalent test location at a previous time.
Guided waves are a specific method for the NDT/SHM of structures or components in which low-frequency (generally <1 MHz) ultrasonic waves are introduced into the structure that subsequently interact with the local boundaries of the structure and form a coherent propagating wave packet that then follows the structure. Such boundaries may be the external surfaces of a particular material or the boundary may be an interface between two materials. The propagation characteristics of the wave packet are dictated by the cross-sectional dimensions and material properties of the structure. Unlike traditional ultrasonic waves that may be used to perform localized testing or inspection, guided waves may be used to perform remote testing or inspection of a material through various NDT/SHM techniques. In the pulse-echo guided wave technique, appurtenances, such as welds, structural attachments, cracks, or metal loss, reflect portions of the wave packet back toward the generating sensor where it is received by the generating sensor or by a separate receiving sensor and then amplified, digitized, processed, and displayed. These reflections may be analyzed to determine the extent of the abnormality or defect as well as the location of such abnormality or defect.
Ultrasonic guided wave techniques are utilized in a wide range of non-destructive inspection applications including those for pipes, plates, and shells comprised of metals, composites, and other materials. Long-range guided wave techniques are often utilized for the inspection of pipelines; technologies currently exist that utilize one of piezoelectric or magnetostrictive means. Some long-range guided wave testing technologies utilize a segmented collar design, in which at least one of the pulser/receiver sensors is divided into discrete segments around the circumference of the pipe. Segmentation allows the sound to be sent and received in a partial loading configuration around the circumference of the pipe. Partial receiving and, in some cases, partial loading, are used to perform both active and synthetic focusing of guided wave energy in the pipe to identify the axial and circumferential location and extent of reflectors. One example of a segmented long-range guided wave testing system that utilizes the magnetostrictive effect is disclosed in commonly assigned U.S. Pat. No. 8,907,665 B2, issued Dec. 9, 2014, entitled “MAGNETOSTRICTIVE SENSOR ARRAY FOR ACTIVE OR SYNTHETIC PHASED-ARRAY FOCUSING OF GUIDED WAVES,” and which is incorporated by reference herein in its entirety.
The present disclosure describes enhanced long-range guided wave pipe inspection systems and methods utilizing segmented magnetostrictive collar technology described in U.S. Pat. No. 8,907,665 B2, which provide enhancements, such as enhanced ease of use, reduced cost, and a significantly extended operating temperature range.